Designing a plated pattern in printed wiring board

ABSTRACT

The plating method comprises the steps of dividing a region, to be plated, into a group of mesh-like zones, measuring a plating area of each of the zones, comparing the measurement values of the plating areas and judging whether or not the plating area has any variance, and conducting a design change, on patterns contained in this zone, to eliminate the variance.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of Ser. No. 10/261,939,filed Oct. 2, 2002, which claims priority of Japanese Patent ApplicationNo. 2002-025941, filed on Feb. 1, 2002, in the Japanese Patent Office,the disclosures of which are incorporated herein in their entirety byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a plating technology. More particularly, theinvention relates to a method, and an apparatus, for controlling platingso as not to create variance in plating areas when a pattern-providingplating film is formed at a predetermined film thickness on a substrate,a control program and a recording medium that are used for such acontrol method and apparatus, and a plating method. As the invention canexactly control the plating area, based on such an exactly controlledplating area, the invention can appropriately assist a design change,such as feedback of design change to a designing department of patterns,and preconsideration of production conditions. Therefore, the inventioncan be used advantageously for producing printed wiring boards, inparticular.

2. Description of the Related Art

Generally speaking, a printed wiring board is produced through a seriesof steps of boring holes in a substrate comprising a copper-cladlaminate board, sequentially applying electroless copper plating andelectrolytic copper plating to form a conductor layer having apredetermined thickness on the entire surface of the board, andselectively etching away unnecessary portions of the conductor layer toform wiring or the like in a desired pattern. Because remarkableprogress has been made in recent years in the higher density of printedwiring boards and their multi-layered construction and a higheroperational speed of devices mounted onto the boards, improvement in andmanagement of plating steps have become very important. For example, ithas been desired to provide a plating method capable of easily copingwith production of a variety of kinds of products in limited quantitiesand with frequent design changes. If plating areas have any variance,the plating thickness becomes small or large, so that electricalcharacteristics are deteriorated and a waste of materials occurs.Therefore, strict management of the plating steps inclusive of theplating area has become necessary.

Japanese Unexamined Patent Publication (Kokai) No. 56-64493, forexample, discloses a production method, for a printed board, which usesa photo-mask to correct a circuit pattern width to cope with variance inthe thickness of electric copper plating in an etching step carried outafter chemical copper plating and electric copper plating in order tominimize variance in the copper plating thickness. Japanese UnexaminedPatent Publication (Kokai) No. 1-321308, now Patent No. 2593690,discloses a plating area measurement apparatus for a printed wiringboard characterized in that means, for calculating a pattern area fromgiven pattern data and means for calculating an inner area of eachthrough-hole from boring data and sheet thickness data, calculate aplating area of a printed wiring board so as to omit an expensive andtroublesome step that uses a negative film for an optical measuringinstrument, when the plating area is measured, to keep the platingthickness constant. Further, Japanese Unexamined Patent Publication(Kokai) No. 2001-123298 discloses an electrolytic plating method thatdetermines in advance a relational formula between an electrodepotential and a current density and determines, on the other hand, acurrent value and a potential value when a plating object is polarizedin a plating bath, calculates a plating area of a plating object fromthe relational formula, the current value and the potential value andconducts plating to a predetermined thickness, so as to reduce avariance in a deposition film thickness of a plating metal.

As described above, attempts have already been made to measure andcontrol variance of the plating area to solve the problem of variance ofthe thickness of the plating film formed on the substrate for formingthe pattern in the production of the printed wiring board according tothe prior art. However, the prior art plating methods have employed onlya method that optically scans the whole surface of one of the surface ofthe substrate and measures the plating area of the substrate as a whole.Therefore, this method cannot measure and adjust variance of the platingareas between top and back surfaces of the substrate. Thus, this methodcannot sufficiently satisfy the recent technical progresses andrequirements described above for the following reasons. If the platingarea is different between a certain plating region and another when aplating film is considered as a single surface (single body) of thesubstrate, variance occurs in the plating thickness (when an additivemethod is used) or in an etching amount (when a subtractive method isused). Further, problems of planarity and warping of the substrateoccur. When an insulating film is formed on or below the plating film,control of the film thickness of the insulating film becomes difficult,and insulating defects and connection defects occur due to a flow of theinsulating resin.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a plating method that solvesthe problems of the prior art technologies described above, can easilycope with production of a variety of kinds of products in limitedquantities and with frequent design changes, can moreover eliminatevariance of plating areas and hence plating film thickness, and cansolve the problems of planarity and warping of a substrate and theproblems of film thickness control of an insulating film.

It is another object of the invention to provide a control method of aplating area useful in the practice of the plating method describedabove.

It is still another object of the invention to provide a control programfor a plating area useful in the practice of the plating methoddescribed above.

It is still another object of the invention to provide a recordingmedium useful in the practice of the plating method described above.

It is still another object of the invention to provide a controlapparatus of a plating area useful in the practice of the plating methoddescribed above.

These and other objects of the invention will be easily understood fromthe following detailed explanation of the invention.

According to one aspect of the invention, there is provided a controlmethod for a plating area for preventing variance of plating areas whena pattern-providing plating film is formed at a predetermined thicknesson a substrate, comprising the steps of: dividing a region, to beplated, of the substrate into a group of mesh-like zones, each havingsubstantially the same area; measuring the plating area of each of thezones; comparing the measurement values of the plating areas and judgingwhether or not variance exists in the plating area in each of the zones;and conducting a design change of patterns contained in any of the zonesto eliminate the variance when the variance of the plating area isjudged as existing in the variance judgment step.

According to another aspect of the invention, there is provided aprogram used in combination with a computer when a pattern-providingplating film is formed at a predetermined film thickness on a substrate,the program causing the computer to execute the steps of: dividing aregion, to be plated, of the substrate into a group of mesh-like zoneseach having substantially the same area; measuring the plating area foreach of the zones; comparing the measurement values of the plating areasand judging whether or not the plating area has variance in each of thezones; and conducting a design change of the patterns contained in anyof the zones to eliminate the variance when the plating area is judgedas having a variance in any of the zones in the variance judgment step.

According to still another aspect of the invention, there is provided acomputer-readable recording medium used in combination with a computerwhen a pattern-providing plating film is formed at a predetermined filmthickness on a substrate, the recording medium storing a program forcausing the computer to execute the steps of: dividing a region, to beplated, of the substrate into a group of mesh-like zones each havingsubstantially the same area; measuring the plating area for each of thezones; comparing the measurement values of the plating areas and judgingwhether or not the plating area has variance in each of the zones; andconducting a design change of the patterns contained in any of the zonesto eliminate the variance when the plating area is judged as having thevariance in any of the zones in the variance judgment step.

According to still another aspect of the invention, there is provided anapparatus for preventing variance of plating areas when apattern-providing plating film is formed at a predetermined filmthickness on a substrate, comprising: a plating region-division unit fordividing a region, to be plated, of the substrate into a group ofmesh-like zones each having substantially the same area; an areameasurement unit for measuring the plating area for each of the zones; avariance judgment unit for comparing the measurement values of theplating areas and judging whether or not variance exists in the platingarea of each of the zones; and a pattern design-changing unit forconducting a design change of patterns contained in any of the zones toeliminate the variance when the plating area is judged as having avariance in any of the zones by the variance judgment unit.

According to still another aspect of the invention, there is provided aplating method for forming a pattern-providing plating film at apredetermined film thickness on a substrate, comprising the steps of:dividing a region, to be plated, of the substrate into a group ofmesh-like zones each having substantially the same area; measuring theplating area for each of the zones; comparing the measurement values ofthe plating areas and judging whether or not the plating area hasvariance in each of the zones; conducting a design change of thepatterns contained in any of the zones to eliminate variance when theplating area is judged as having a variance in any of the zones in thevariance judgment step; and subjecting the substrate to a plating stepunder the condition where the plating areas do not substantially havethe variance in all of the zones.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view showing an example of a printed wiring board usedin the practice the invention;

FIG. 2 is a flowchart showing an example of a plating area controlmethod according to the invention;

FIGS. 3A and 3B are plan views illustrating a surface data-creating stepin the plating area control method according to the invention;

FIGS. 4A and 4B are plan views illustrating a divided surfacedata-creating step in the plating area control method according to theinvention;

FIGS. 5A, 5B and 5C are plan views illustrating a surface data-punchingstep in the plating area control method according to the invention;

FIGS. 6A and 6B are plan views illustrating other results of the surfacedata-punching step;

FIGS. 7A and 7B are plan views illustrating a measurement data-punchingstep in the plating area control method according to the invention;

FIG. 8 is a plan view illustrating an example of measurement dataobtained in the plating area control method according to the invention;

FIG. 9 is a plan view illustrating another example of measurement dataobtained by the method according to the invention;

FIG. 10 is a plan view illustrating another example of measurement dataobtained by the method according to the invention;

FIG. 11 is a plan view illustrating another example of measurement dataobtained by the method according to the invention;

FIG. 12 is a perspective view illustrating a computer system, i.e.,control apparatus, used in the practice of the invention, and a programand a recording medium that are used for the computer system; and

FIG. 13 is a flowchart showing the constitution of a monitor used in thecomputer system shown in FIG. 12.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

This invention relates to a plating method for forming a plating film,for use in pattern, to a predetermined film thickness on a substrate asan underlying base, a control method for a plating area useful for sucha plating method, a control program for a plating area, a recordingmedium for controlling a plating area and a control apparatus for aplating area.

The plating method according to the invention and the control method ofthe plating area etc., used for the plating method, can be appliedbroadly and advantageously to plating steps, in general, used forproducing semiconductor devices, printed wiring boards, and so forth,and its application range is not limited. Since the invention isparticularly useful in the plating step used for producing the printedwiring boards, the present invention will be hereinafter explained indetail with reference to this plating step.

In the practice of the present invention, the plating method is carriedout in accordance with an additive method or a subtractive methoddepending on a structure of a desired printed wiring board. Thesemethods are generally carried out while a substrate, i.e., a platingobject, as the underlying base is immersed in a plating solution havinga predetermined composition. The plating solution can be broadlyclassified into an electrolytic plating solution and an electrolessplating solution. These plating solutions are not particularly limitedand can have the same composition as that of a plating solution that isgenerally used for producing semiconductor device and, more concretely,multi-layered wiring boards.

The electrolytic plating solution contains ions of a metal to be plated,reduces the metal ions through electrolysis and can cause the metal ionsto precipitate in the form of a metal film on an electrically conductivemetal material connected to a cathode. The metals to be contained in theelectrolytic plating solution (hereinafter, also referred to as “platingmetals”) are not limited to the following examples but generally includecopper, nickel, solder, rhodium and gold. These metals may be usedeither alone or in combination of two or more metals. More concretely,in the case of a copper plating solution, a plating bath can be broadlyclassified into an acidic bath and an alkaline bath. The platingsolution for the acidic bath is a copper sulfate plating solution, andthe plating solution for the alkaline bath includes a copper cyanideplating solution and a copper pyrophosphate plating solution. Numeroustechnical references describe the compositions of the electrolyticplating solution and the electroless plating solution and the platingmethods. Therefore, a detailed explanation will be omitted.

The production of the printed wiring board by the use of the platingmethod of the invention can be carried out by basically employing thoseprocesses that are known to those skilled in the art and have generallybeen employed in the past, either as such or by arbitrarily changingthem. Therefore, a detailed explanation of individual productionprocesses for executing the invention will be omitted.

An example of a process for producing a printed wiring board inaccordance with the present method will be hereinafter explained.

First, a double-face copper-clad laminate board is prepared as an objectof plating. This double-face copper-clad laminate board includes aninsulating resin substrate and a copper foil bonded to each surface ofthe resin substrate. Next, through-holes are bored in such a method asto penetrate through the laminate board. A drilling machine can be usedfor boring. Next, electroless copper plating is applied to the wholeexposed surface of the laminate plate to form a thin electroless copperplating film. Subsequently, an electrolytic copper plating film isapplied by using the electroless copper plating film as a cathode.Thereafter, unnecessary portions of the copper foil, the electrolesscopper plating film and the electrolytic copper plating film, that areformed over the surface of the laminate board in lamination, are etchedaway. As a result, there is obtained a conductor pattern that covers theinner wall of the through-holes and extends to the surface of thelaminate board.

After the conductor pattern is formed as described above, formation of awiring pattern and mounting of a semiconductor chip are carried out in acustomary manner to give a printed wiring board having a desiredstructure. Though the example given above uses one double-facecopper-clad laminate board, it is of course possible to use asingle-face copper-clad laminate board or a printed wiring board havinga multi-layered structure in place of the double-face copper-cladlaminate board.

When the plating step described above is carried out, the inventioncontrols the plating area, adjusts the areas of divided plating regionsto avoid variance among the plating areas, and then produces the printedwiring board in a customary manner. Such a control method of the platingarea will be explained with a control program of a plating area, arecording medium for controlling a plating area and a control apparatusof a plating area that are associated with the control method of theplating area, with reference to the accompanying drawings.

FIG. 1 shows an example of a printed wiring board as a typical exampleof the plating object according to the invention. As shown, the printedwiring board 10 includes minute and complicated wiring patterns andlands that are disposed at a high density. When producing such a printedwiring board, a conventional plating technology employs a method thatoptically and entirely scans only one of the surfaces of the substrateand collectively measures the overall plating area of the substrate.Therefore, this method can measure and adjust only variance of theplating areas between top and back surfaces of the substrate, and thuscannot cope with the recent remarkable progress of technologies.Further, the conventional method cannot flexibly cope with theproduction of a variety of kinds of products in limited quantities andwith frequent changes of design, either. In contrast, this invention hasfound a novel measurement method of a plating area that divides a platedregion into a large number of zones (cells) and measures the platingarea of each zone. Unexpectedly, this invention provides remarkableoperations and effects such that the method can correctly executecorrection of production and design changes, can improve planarity ofthe substrate, can control the plating thickness, the etching amount andthe thickness of an insulating layer, and can prevent insulation defectsand connection defects.

When the plating area is controlled in accordance with the invention,the plated region of the printed wiring board is divided into a largenumber of zones, preferably a group of mesh-like zones havingsubstantially the same area. This zone division step can be preferablycarried out by combining a plurality of rows aligned in a transversedirection with a plurality of columns aligned in a longitudinaldirection. This zone division step will be explained with reference tothe printed wiring board 10 shown in FIG. 1. Rows (1, 2, . . . , 12)aligned in the transverse direction and columns (A, B, . . . , M)aligned in the longitudinal direction provide a group of mesh-like zones(A1, B1, . . . , F6, . . . , M12). Each zone to be measured generallyhas the same shape and the same size, but may have differences to acertain extent within an allowable range. As can be easily understood,when the printed wiring board is viewed under the divided state inaccordance with the invention, the plating area generally has a largedifference among the zones. Therefore, the invention that can easilycontrol the plating area and has extremely large significance. In theillustrated example, one plating region is divided into 144 zones intotal. However, the plating area may be divided into a greater orsmaller number of zones, whenever necessary. In other words, thedistribution of the zones to be measured may be coarse or dense inaccordance with a distribution density of wiring patterns, etc.Furthermore, the zones to be measured may have shapes, such astriangular, other than square.

After the plated region is divided into a large number of zones asdescribed above, the plating area of each zone is measured. The platingarea can be measured either optically or electrically in a customarymanner. If necessary, the plating area may be measured in accordancewith the means described in the above-cited Japanese Unexamined PatentPublications.

After measurement of the plating area of each zone is complete, themeasurement value of the plating area of each zone is compared to judgewhether or not the plating area of each zone has variance. Here, themeasurement value of the plating area can be electrically compared inaccordance with a customary method.

When variance of the plating area is judged as existing in any of thezones in the variance judgment step of the plating area, the wiringpatterns contained in that zone are checked again and a design change ismade, whenever necessary. When the plating area is excessively great,for example, a design change, such as movement and reduction of thepattern, is made so as to reduce the plating area. When such a designchange is made, a plating area that is balanced, as a whole, can beacquired.

After the design change is completed, the plating area measurement stepand the variance judgment step described above are again repeated. Whenthe problem of variance is judged as being eliminated, a production stepof the printed wiring board is started as scheduled.

FIG. 2 is a flowchart showing a control method of a plating area in theproduction of the printed wiring board as a suitable example of theinvention. The control method of the plating area shown in the drawingincludes a step S1 of generating surface data having the same size asthat of a plating area of a plating object (here, a maximum outside sizeof the printing wiring board); a step S2 of arranging surface data(surface data of a divided size) corresponding to a size of a zone to bedivided in accordance with the invention inside the surface datagenerated in the step S1, by means of a separate picture layer; a stepS3 of punching the surface data of the step S1 by the surface data ofthe divided size of the step S2; a step S4 of punching the data of thearea of the plating object (data to be measured) by the data obtained inthe step S3; a step S5 of calculating the plating area from the data ofeach zone obtained in the step S4; a step S6 of judging whether or notthe numeric value of each plating area calculated by the step S5 hasvariance; and a step S7 of conducting a design change of a wiringpattern, etc., to eliminate variance when variance is judged as existingin the step S6 (see, No). When variance is not judged as existing in thestep S6 (see, Yes), the production of the printed wiring board isstarted.

The steps S1 to S4 described above will be explained in sequence withreference to FIGS. 3A and 3B to FIG. 11.

In the step S1, as shown in FIG. 3B, a surface data (hereinafter called“data A”) having the same size as the maximum outside size of theprinted wiring board 10 previously explained with reference to FIG. 1and again shown in FIG. 3A is generated. The data A is a database thatcan erase all the plating area data of the printed wiring board to bemeasured, and is in a sense a masking data.

In the step S2, as shown in FIG. 4B, the surface data (surface data ofthe divided size: hereinafter called “data B”) corresponding to the sizeof the zone to be divided in accordance with the invention is arrangedas a separate picture layer inside the surface data (data A) generatedin the preceding step S1 shown in FIG. 4A. In other words, the data B isfor selectively erasing the data A in subsequent steps. The zone of thedata B corresponds to the measured zone (A1, B1, F6, . . . ) of theprinted wiring board shown in FIG. 1 but, it should be noted that inFIG. 4B, the total number of the zones is increased from 144 of FIG. 1to 788 for convenience of explanation. Note also that FIG. 4B includesthick dividing lines to easily explain the presence of the adjacentzones, but in the adjacent zones, the zones contact with each otherwithout any gap or dividing line.

After the data A and the data B are created in the manner describedabove, in the step S3, the surface data of the measured zone Al ispunched out from the surface data (data A) of the step S1 shown in FIG.5A by using one surface data (data B) of the step S2 shown in FIG. 5B,i.e. data B-A1, to create a clear state. In other words, there isobtained data C in which the surface data of the measured zone A1 isselectively erased from the data A as shown in FIG. 5C.

In the step S3, the data-punching step is executed for all the measuredzones, and the number of data C corresponding to the number (788) of thesurfaces of the data B can be obtained. FIGS. 6A and 6B show additionaltwo examples of the resulting data C.

In the step S4, the data of the plating area of each measurement zone ispunched out by using the data C obtained in the step S3 to create theclear state. For example, only the surface data of the measured zone A1can be punched out from the data A shown in FIG. 7A by using one of thesurface data in the step S3 shown in FIG. 7B, that is, data C-A1, tocreate the clear state. As a result, there is obtained data D in whichonly the measured zone A1 is cleared as shown in FIG. 8.

In the step S4, the data-punching step described above is executed forall the measured zones, and the number of data D corresponding to thenumber (788) of the surfaces of the data B can be obtained. FIGS. 9 to11 show three additional examples of the resulting data D.

After the data D is obtained through a series of steps described above,in the step S5, the plating area is calculated from the data D of eachzone obtained in the step S4.

After the calculation of the plating area, the step S6 judges whether ornot any variance exists in the numeric value of each plating area socalculated. This judgment step can be advantageously executed in acustomary manner by using a personal computer in combination withcommercial software such as CAM and the like.

When the judgment result proves “variance exists in plating area” (No)in the step S6, a design change such as a pattern arrangement of thewiring patterns and the lands, the land width, etc., is made so as toeliminate large variance in the respective plating areas. A concreteexample of this design change is as follows, though it is in no wayrestrictive. Namely, additional patterns are disposed in the regionshaving low numerical values (where the pattern density is low) and thepatterns are skipped in the regions having high numeric values to reducethe pattern density. After the design change is made in the step S7, theflow again returns to the step S4 in order to judge whether or not thisdesign change is appropriate, and the steps S5 and S6 are repeated.

When the judgment result is “No variance in plating area” (Yes) in thestep S6, the execution of the step S7 is no longer necessary, and theproduction of the printed wiring board is started in a customary manner.

In addition to the control method of the plating method described above,the invention provides a program for controlling the plating area, aninformation recording medium storing such a control program, and acontrol apparatus of the plating area.

In the program for controlling the plating area, the program is used incombination with a computer when a pattern-providing plating film isformed at a predetermined film thickness on a substrate. The programcauses the computer to execute a step of dividing a plated region of thesubstrate into a group of mesh-like zones each having substantially thesame area; a step of measuring the plating area for each of the zones; astep of comparing the measurement values of the plating areas andjudging whether or not the plating area has variance in each of thezones; and a step of conducting a design change for the patternscontained in any of the zones to eliminate the variance when the platingarea is judged as having the variance in any of the zones in thevariance judgment step.

The information recording medium according to the invention has storedtherein the program for controlling the plating area described above.

The control apparatus of the plating area according to the invention isfor preventing variance of the plating area when a pattern-providingplating film is formed at a predetermined thickness on a substrate. Theapparatus comprises a plating region-division unit for dividing aregion, to be plated, of the substrate into a group of mesh-like zoneseach having substantially the same area, an area measurement unit formeasuring the plating area for each of the zones, a variance judgmentunit for comparing the measurement values of the plating areas andjudging whether or not variance exists in the plating area of each ofthe zones, and a pattern design-changing unit for making a design changeof patterns contained in any of the zones to eliminate the variance whenthe plating area is judged as having the variance in any of the zones bythe variance judgment unit.

FIGS. 12 and 13 are intended to concretely explain the inventionsdescribed above. FIG. 12 is a perspective view typically showing amethod and an apparatus each for installing to a monitor the controlprogram and its recording medium used in the plating area control methodof the invention. FIG. 13 shows a constitution of the monitor shown inFIG. 12.

The monitor (hereinafter called a “computer system”) shown in FIG. 12includes a main unit 101, a display 102 for displaying information suchas images on a display screen 102 a in accordance with an instruction ofthe main unit 101, a keyboard 103 for inputting various kinds ofinformation to the computer system 100, a pointing device (mouse) 104for designating an arbitrary position on the display screen 102 a of thedisplay 102 and a modem 105 connected to a public line.

As shown in FIG. 13, the main unit 101 includes CPU, RAM, ROM, a harddisk drive (HDD), a CD-ROM drive and an FD drive, an I/O interfaceconnected to the display 102, the keyboard 103 and the mouse 104, and aLAN interface for gaining access to the database connected through acommunication line. These devices are connected to one another through abus 112.

The program of the invention stored in the CD-ROM 110, the floppy™ disk(FD) 111, a portable recording medium (not shown) such as a DVD disk, anopto-magnetic disk or an IC card or the database connected through thecommunication line by using the modem 105 or the LAN interface isinstalled in, and executed by, the computer system 100. The program ofthe invention so installed is stored in the hard disk (HD) in the HDDand is executed by CPU by utilizing the RAM or the like.

Here, the recording medium storing the program of the invention includesnot only the portable type recording media such as the CD-ROM 110, theFD 111, the DVD disk, the opto-magnetic disk, the IC card, etc., and astorage device provided to the inside/outside of the computer system 100such as the hard disk drive, but also a database holding the program ofthe invention of the installation destination and connected through thecommunication line, such as another computer system (PC) connected tothe computer system 100 through the LAN and indicated by referencenumeral 113 or a database of a server and furthermore, a transfer mediumon the communication line.

As explained above in detail, the invention can provide a plating methodthat can easily cope with production of various kinds of products inlimited quantities and with frequent design changes, can eliminatevariance of a plating area and, hence, variance of a plating filmthickness, and can solve the problems such as planarity and warping of asubstrate and film thickness control of an insulating film.Particularly, the invention can aid design of a printed wiring board,etc., in a data provision stage, can prevent insulation defects andcontact defects in resulting products and can drastically improve ayield of the products.

Further, the invention provides a control method of a plating area, acontrol program of a plating area, a recording medium for controlling aplating area and a control apparatus of a plating area that arealtogether useful for executing the plating method of the invention.

1. A plating method for forming a pattern-providing plating film at apredetermined film thickness on a substrate, comprising the steps of:dividing a region, to be plated, of the substrate into a group ofmesh-like zones each having substantially the same area; measuring theplating area for each of the zones; comparing the measurement values ofthe plating areas and judging whether or not the plating area hasvariance in each of the zones; conducting a design change on thepatterns contained in any of the zones to eliminate variance when theplating area is judged as having the variance in any of the zones in thevariance step, and subjecting the substrate to a plating step under thecondition where the plating areas do not substantially have variance inany of the zones.
 2. A plating method according to claim 1, wherein rowsand columns respectively aligned in transverse and longitudinaldirections divide the region to be plated and define the mesh-likezones.
 3. A plating method according to claim 1, wherein the method isused for producing a printed wiring board.
 4. A plating method accordingto claim 2, wherein the method is used for producing a printed wiringboard.